DescriptionEye bilobed, the upper lobe 1 to 2 times as wide as the lower lobe. The transverse region between the two lobes is scarcely constricted, and has a lightly pigmented band [N.boopis eye & rostrum ].Peduncle of first antenna with lobe on the first segment that is upright, narrow (in lateral view), distally rounded, and hood-like, extending above the base of the second segment [N.boopis ped 1stN.boopis lappet ]. Rostrum absent [N.boopis eye & rostrum ]. Carapace with broadly triangular frontal plate, extending to the posterior limit of the eye. The gastric region is somewhat elevated anterior to the cervical groove but not domed, and with a short, low keel anteriorly. The carapace is without lateraldenticles. Thoracic leg 3 greatly elongated, naked and terminating in an apical tuft of bristles [N.boopis-drawing ].Abdomen without median spines or keels. The sixth segment is twice as long as high [N.boopis-drawing ].Petasma: the terminal process is broad at the base, then narrows abruptly, with the distal two-thirds broadened and the tip with a shallow fold-like depression which is overhung by a low, short, acute projection. The proximal process is slender, longer, and arcs in a semi-circle. The lateral process is almost straight, and is acutely hooked. The hooked additional process is shorter[N.boopis petasma ]. Reproduction: nothing is known about the breeding of this species (Mauchline, 1984).

LengthAdults are 20-25 mm.

Larval stagesN.boopis-A

EcologyN. boopis has been reported in the stomachs of planktivorous fishes.

Depth rangeMesopelagic; adults usually below 300 m (500-600 m according to Mauchline, 1984). They are not vertical migrators.

Distribution in the North SeaN. boopis is absent from the shallow North Sea, but records are known from the northeren entrance (S. Hay, pers. com.).

World distributionWidely distributed in the N and S Pacific 42°N-53°S, in the Atlantic 65°N-53°S, and the Indian Ocean, 10°N to about 50°S.